Abstract : The absorption spectra of chromium(III) and nickel(II) at octahedral sites in a zirconium barium fluoride glass are analyzed and compared with vitreous and crystalline mixed oxides, suggesting slightly longer Cr-F and Ni-F distances than in crystalline fluorides. Laser properties of rare earth ions in fluoride glass (ZBLA) having composition of 57ZrF4, 34BaF2, 5LaF3, 4A1F3, or (PBLA) having composition of 36PbF2, 24ZnF2, 35GaF3, 3YF3, 2A1F3, for Nd(III) were calculated. Pumping efficiencies, lifetimes of excited and terminal levels and stimulated peak cross-sections are presented. It is shown that multiphonon relaxations (in the case of energy difference less than 3000 cm-1) are always orders of magnitude lower in the fluoride glass than in the tellurite glass and the inhomogeneous width is consistently smaller in fluoride glass than in tellurite glass, which was chosen as a model for oxide glass. No significant difference was found for concentration quenching between the two kinds of glasses. Energy transfer between Mn(II) and Nd(III) can increase pumping efficiencies of Nd(III) lasers. Keywords: Israel.